1. Field of the Invention
This invention relates to the stabilization of talc-based powder compositions containing a pharmaceutically acceptable acid addition salt of an antimicrobial sulfur containing 1-substituted imidazole compound. Stabilization is achieved by adding a stabilizing amount of a basic metal salt of an inorganic or organic acid.
2. Prior Art
1-Substituted imidazoles and their acid addition salts are but one of a large number of compounds known to be effective for treating fungal, bacterial and protozoal infections. These imidazoles are particularly effective as antifungals, but also have antibacterial and antiprotozoal characteristics.
Generally they are administered to plants, seeds, and soils in the form of sprays, powders or the like. They may be administered to animals in a topical form or by oral administration. One of the more frequently utilized methods of administration is to formulate these antimicrobial imidazoles into powders, particularly powders prepared with a talc diluent. Such powders or dust provide a convenient route for treating soils, disinfecting containers, structures, or the like, for treating seeds and plants, and for treating dermal and other conditions in animals.
Talc-based powder formulations of some sulfur containing L-substituted imidazole acid addition salt compounds were found to show active ingredient degradation during storage under accelerated and normal shelf-life conditions. It has been found that this degradation can be retarded or prevented by adding basic salts of inorganic or organic acids to these talc-based powders.
Talc-based powders containing special ingredients to prevent degradation of a second component are known. For example, U.S. Pat. No. 4,185,086 discloses the addition of polyethylene glycol to talc compositions in order to improve the stability of added fragrances. In another instance, U.S. Pat. No. 3,801,709 describes the use of chelating agents, particularly disodium EDTA or tetrasodium EDTA, as a means for stabilizing talc compositions containing added perfumes. Two Japanese authors, Tetsuya Takahashi and Ryuichi Yamamoto, set out the isomerization effects talc and calcium carbonate excipients have on vitamin D.sub.2 in a series of articles published in the periodical Yajugaku Zasshi. There are seven articles in the series which begins at page 914 of vol 89(7), (1969) and running on consecutive pages through page 946 of the same volume of that periodical. None of these references disclose the use of basic metal salts of inorganic or organic acids to prevent talc induced degradation generally, or talc induced degradation of sulfur containing 1-substituted imidazole acid addition salts specifically.